Courtesy of SegmentNext.com
In case you didn't already know, beating the game allows you to play the other characters story, which will be somewhat different. You'll need to do each story, Leon A and Claire B; then Claire A and Leon B.
For optimal results, make a seperate save BEFORE using the cable car to access the Lab, this is the point of no return to the Police Station, compare to this list and backtrack if needed. Some parts are locked, such as Ada's part, after you finish them, so stay vigilant.
The last one I needed, after several playthroughs, was file #50, in the bathroom where Irons washes the chemicals off his face when you play as Claire.
Leon A
Starting with Leon A would be better as most of the files will be found under this part. Locations for these files are listed down below:
File #1: Orientation Letter
In your inventory from the start of the game.
File #2: Officer’s Notebook
Police Station 1F, Watchman’s Room.
File #3: Record of Events
Northwest in Police Station 1F, Operations Room.
File #4: Uses of Gunpowder
Police Station 1F, West Office. Inside on the desk.
File #5: Operation Report
Police Station 1F, West Office. On the side of the desk.
File #6: Rookie’s First Assignment
Police Station 1F, West Office. At the end of the desk.
File #7: Storage Locker Terminal Memo
Police Station 1F, Safety Deposit Room
File #8: Medical Benefits or Herbs
Police Station 1F, Dark Room.
File #9: Portable Safe Instructions
Police Station 2F, Shower Room
File #10: To Any Survivors
Police Station 3F, at the end of the hallway.
File #11: Some Guy’s Scribblings
Police Station 3F, West Storage Room.
File #12: Guide Pamphlet
Police Station 2F, on the counter in the Waiting Room.
File #13: Art Article “The Red Stone”
Police Station 2F, on the chair in the Art Room.
File #14: Internal Memo
Police Station 2F, S.T.A.R.S. Office, behind the desk.
File #15: Memo “Jail Power Panel”
Police Station B1, at the end of the Jail.
File #16: Autopsy Record 53477
Police Station B1, inside the Morgue.
File #17: Equipment Disposal Notice
Police Station B1, Firing Range.
File #18: A Message from Mr. Raccoon
Police Station B1, on the counter in Firing Range.
File #19: Confiscation Report
Police Station 1F, on a shelf in Observation Room.
File #20: Letter to S.T.A.R.S. Members
Police Station 2F, armory in STARS room.
File #21: Repair Plan
Police Station 3F, straight in front of you when you enter the Clock Tower.
File #22: Ben’s Memo
Police Station B1, in Ben’s Cell in the Jail.
File #23: Interview Transcript
Police Station B1, in Ben’s Cell in the Jail from his corpse.
File #24: Sept. Inspection (Week 1)
In the room where you encounter your first zombie as Ada.
File #25: Sept. Inspection (Week 2)
Incinerator Room as Ada.
File #26: Copy of Emails to Umbrella HQ
Sewer: upper, on the table in the Control Room.
File #27: Sewers Company Pamphlet
Sewer: middle, Monitor Room.
File #28 Unlocking the U-Area Door
Sewer: middle, Monitor Room.
File #29: Delivery Receipt
Sewer: middle, Treatment Pool Room.
File #30: Jazz Festival Flyer
Sewer: upper, Worker’s Waiting Room.
File #31: Nap Room Log
In the reception hall of the Laboratory.
File #32: ID Wristband
Laboratory, Reception. In the room where there is a typewriter.
File #33: Special Forces Recording
North of the Laboratory.
File #34: Herbicide Synthesis
Laboratory, on the table in the Drug Testing Lab.
File #35: Somebody’s Note
Laboratory B1, Room south of Lobby. On a chair.
File #36 Wayne Li’s Inbox
Laboratory B2, on the PC in the Low-Temp Testing Lab.
File #37: Byron Cartwrights Inbox
Laboratory B1, in the Presentation Room.
File #38: Wayne Li’s Note
Laboratory B1, in the Nap Room.
File #39: William Birkin’s Inbox
Laboratory B1, on the PC of the Biotesting Lab.
File #40: Research Diary
Laboratory B1, P-4 Level Testing Lab on the PC.
Claire A
Following are the files that you that you can find during Clair A campaign.
File #41: Letter from Best Friend
In your inventory from the start of the game.
File #42: Uses of Gunpowder
Police Station 1F, Watchman’s Room. Same place as Leon’s but with different content.
File #43: Raccoon Monthly, June Issue
Police Station B1, in the Elevator Control Room.
File #44: Copy of Emails to Chief Irons
Police Station 2F, inside the Chief’s Office.
File #45: Taxidermy Log
Police Station 2F, in the middle of Chief’s Office.
File #46: Repair Shop Letter
Police Station 2F, on a shelf in the Private Collection Room.
File #47: Sally’s Diary
In the hallway outside the bedroom where you start off as Sherry.
File #48: Tom’s Diary
In the front hall after going downstairs as Sherry.
File #49: Diary
In the Director’s Room while playing as Sherry.
File #50: Letter from the Director
Inside the bathroom of Orphanage 2F.
File #51: Report about “G”
Sewers, on the whiteboard in the office.
File #52: IMPORTANT NEST-Wide Alert
Laboratory, on the PC in the Security Room.
Leon B
Following are the files that you that you can find during Leon B campaign.
File #53: Scrap of Paper
Police Station 1F, on the table in the Watchman’s Room.
File #54: Notebook with Missing Page
Police Station 1F, in the Main Hall where we encountered Marvin.
File #55: Claire’s Memo
Police Station 2F in the STARS Office.
File #56: Claire’s Note
Sewer: middle, in the Treatment Pool Room.
Claire B
Following are the files that you that you can find during the Claire B campaign.
File #57: Leon’s Memo
Police Station 2F in the STARS Office.
File #58: Leon’s Note
Sewer: middle, in the Treatment Pool Room.
If something is missing, please comment. I'm currently playing through to ensure this is accurate, but also started a new job, so my time is limited.